1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition, a monomer, a polymer, and a production method of a radiation-sensitive resin composition.
2. Discussion of the Background
A semiconductor device (e.g., IC or LSI) production process utilizes lithographic microfabrication using a photoresist composition. Along with an increase in the degree of integration of integrated circuits, it has become necessary to form a sub-micrometer or quarter-micrometer fine pattern. Therefore, i-lines, KrF excimer laser light, or ArF excimer laser light having a short exposure wavelength have been used instead of g-lines. Development of lithography utilizing electron beams, X-rays, or EUV light instead of excimer laser light has also progressed.
Lithography utilizing electron beams or EUV light is considered to be next-generation or third-generation patterning technology, and requires development of a resist that exhibits high sensitivity and high resolution. In particular, an increase in sensitivity is very important for reducing the wafer processing time. However, when increasing the sensitivity of a resist that is used for electron beams or EUV light, a deterioration in resolution and an increase in nano-edge roughness occur. Therefore, development of a resist achieving these properties in combination has been strongly desired. Note that the term “nano-edge roughness” refers to a phenomenon in which the edge of the resist pattern irregularly changes with respect to the substrate in the direction perpendicular to the line direction due to the properties of the resist, so that a difference occurs between the design dimensions and the actual pattern dimensions when viewed from above. The difference from the design dimensions is transferred by an etching step that uses the resist as a mask, and causes a deterioration in electrical properties. As a result, a decrease in yield occurs. In particular, it is very important to reduce the nano-edge roughness when forming a fine pattern having a line width of 0.25 μm or less. High sensitivity, high resolution, an excellent pattern shape, and a low degree of nano-edge roughness have a trade-off relationship. It is very important to achieve these properties at the same time.
It is also important to achieve high sensitivity, high resolution, an excellent pattern shape, and a low degree of nano-edge roughness at the same time when using lithography that utilizes KrF excimer laser light or ArF excimer laser light.
As a resist suitable for a lithographic process utilizing KrF excimer laser light, electron beams, or EUV light, a chemically-amplified resist utilizing an acid catalytic reaction has been mainly used from the viewpoint of increasing sensitivity. A chemically-amplified resist composition containing mainly a phenolic polymer (phenolic acid-labile polymer) that is insoluble or scarcely soluble in an alkaline solution, but becomes soluble in an alkaline solution due to an acid, and an acid generator, has been effectively used as a positive-tone resist.
A chemically-amplified resist has also been used as a resist that is suitable for a lithographic process utilizing ArF excimer laser light. A chemically-amplified resist composition containing mainly an acid-labile group-containing (meth)acrylic polymer that becomes alkali-soluble due to an acid, and an acid generator, has been effectively used as a positive-tone resist.
A resist composition containing a phenolic acid-labile polymer obtained by copolymerizing an acid-labile acrylate monomer, and a compound (sulfonic acid generator) generating a sulfonic acid upon exposure to active rays or radiation, has been known as such a positive-tone resist. Positive-tone resist compositions are disclosed in, for example, U.S. Pat. No. 5,561,194 B, JP 2001-166474 A, JP 2001-166478 A, JP 2003-107708 A, or JP 2001-194792 A.